Manhole cover cap

ABSTRACT

A manhole cover cap, for an access cover of an opening into an underground utility structure, can be used to raise the level of an access, or manhole, cover, and to prevent water inflow. The cover cap includes upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, and comprises a rubber material.

FIELD OF THE INVENTION

[0001] The invention relates to a cap for an access cover of an opening into an underground utility structure.

BACKGROUND OF THE INVENTION

[0002] A costly problem commonly faced by municipalities is the need to raise the level of sub-grade manhole, or access, covers, especially when re-paving a roadway. In the context of the present invention, a manhole is an opening with a detachable cover which gives access to an enclosed area and includes such structures as catch basins, sealed inlets, drop-in lids and access ports to shut off valves for water and gas lines. The terms ‘access cover’ and ‘manhole cover’ are used interchangeably herein, and include covers for utility manholes, including electric, gas, telephone and fiber optic facilities, catch basins, sealed inlets, drop-in lids and underground shut off valves for water and gas lines. Since at least two inches of asphalt is generally added to the surface of the roadway as part of the repaving procedure, sub-grade manhole covers are the result. These can be a safety hazard for both vehicles and pedestrians using the roadway, and it is frequently desirable to raise the level of the manhole covers when the roadway is repaved.

[0003] While retrofitting devices to raise manhole covers are known and are used to some extent, these devices have not gained wide acceptance. Rather, it is common practice for a crew to excavate the manhole, remove the frame, recast the concrete of the mouth of the manhole and finally, reset the frame and cover at a higher level. This tedious process is both costly and time consuming, particularly in view of the large number of manholes in a typical street: on average, eighteen in one city block.

[0004] This concern/problem occurs not only in the re-paving situation, but in any situation where the manhole cover is not level with grade, including sunken manholes and low lying field inlets, for example. Therefore, there is a need for a cost effective method for raising the level of a manhole cover.

[0005] Another problem encountered with manholes is inflow of drainage water carrying silt through the junction between the manhole cover and the manhole cover frame. This water can flood underground utility vaults, and add to the volume of sewage water in wastewater treatment plants, increasing treatment costs. Water and gas shutoff valve chambers can become clogged with silt remaining after inflow water has evaporated, hindering access to the valves. Accordingly, there is a need for a way to seal the junction between the manhole cover and frame, and prevent this inflow.

SUMMARY OF THE INVENTION

[0006] It has been unexpectedly discovered that a cover cap according to the present invention, for an access cover for an opening into an underground utility structure, can be used cost-effectively to raise the level of an access, or manhole, cover, and to prevent water inflow. The cover cap includes upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, and comprises a rubber material. The cover cap may be disposed over at least a part of the manhole frame, shielding the juncture between the manhole cover and the frame, and preventing inflow.

[0007] In another aspect, the present invention relates to a method for raising the level of an access cover of an underground structure by a predetermined amount. The method comprises fitting to the access cover a cap comprising upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, having a thickness generally corresponding to the predetermined amount, and comprising a rubber material; and attaching the cap to the access cover; whereby the level of the access cover is raised.

[0008] In yet another aspect, the present invention relates to a method for repaving a roadway having at least one access cover for an opening into an underground utility structure set therein with a layer of pavement having a predetermined thickness. The method includes fitting to the access cover a cap comprising upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, having a thickness generally corresponding to the predetermined thickness and comprising a rubber material; attaching the cap to the access cover to form a cover cap combination; and applying the layer of pavement to the roadway such that an upper surface of the cover cap combination is substantially flush with the upper surface of the layer of pavement.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is an elevational view of a manhole structure, including a cover cap, manhole cover and manhole cover frame for seating the cover.

[0010]FIG. 2 is a cross sectional view of the same manhole structure as shown in FIG. 1.

[0011]FIG. 3 is an elevational view of a cover cap according to the present invention, having drainage holes.

[0012]FIG. 4 shows cross sectional views of means for attaching the cover cap to a manhole cover: FIG. 4a. adhesive; FIG. 4b, bolting means, and FIG. 4c, clamping means.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Referring to the drawings, FIGS. 1 and 2 show an assembly 10 which includes a cover cap 12 according to the present invention, a manhole cover 14 and a manhole cover frame 16. Manhole cover frame 16 surrounds manhole opening 18 and seats or supports manhole cover 14. FIG. 2 shows assembly 10 in cross-section. Cover cap 12 comprises upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening 18, adapted for attachment to manhole cover 14 and comprising a rubber material. The upper and lower surfaces cover cap 12 are parallel or generally parallel. In situations where manhole opening 18 is located in a sloping part of a road (not shown), one of the surfaces may be inclined relative to the other so that the cover cap tapers in wedge-like manner throughout its width. The upper and lower surfaces maybe generally flat or may be patterned in some way as, for example, to increase traction.

[0014] Cover cap 12 is composed of a rubber material. Use of a rubber material minimizes the weight of the combination of cover cap 12 and manhole cover 14, allowing the combination to be removed as easily as manhole cover 14 alone. In addition, and in contrast to ‘harder’ polymeric materials, that is, those having a higher T_(g), the rubber material is resistant to cracking in cold weather.

[0015] The rubber material can be any natural or synthetic rubber or combination thereof, such as saturated or unsaturated polyalkylene rubbers, containing residues derived from at least one olefin comonomer, including monoolefins, such as ethylene, alpha-alkenes with 3-8 carbon atoms, for instance, propylene and/or 1-butene, isobutylene, and also diolefin monomers, such as butadiene and isoprene. If desired, residues derived from polyethylenically unsaturated compounds with non-conjugated double bonds, may be included, for instance, 1,4-hexadiene, dicyclopentadiene, 5-methylene-2-norbomene, 5-ethylidene-2-norbornene and 5-isopropylidene-2-norbornene. Exemplary rubber materials, therefore, include natural rubber, synthetic polyisoprene, styrene-butadiene rubber, butyl rubber, bromobutyl rubber, chlorobutyl rubber, any of the neoprenes, ethylene propylene rubbers, nitrite elastomers, polyacrylic rubber, polysulfide polymers, silicone elastomers, ethylene acrylic elastomers, vinyl acetate ethylene copolymers, chlorinated or chlorosulfonated polyethylenes, and mixtures thereof. The rubber material may also include any of the usual additives such as oil, carbon black, and/or other fillers, zinc oxide, and stearic acid.

[0016] In one embodiment, the rubber material may be a composite derived from rubber particles and a polymeric binder, and optionally, reinforcing fibers. The rubber particles may be ground from any suitable vulcanized or unvulcanized rubber or mixture thereof which can be ground in any suitable manner under any suitable conditions, crogenically or ambiently. The rubber may be obtained from cured or uncured rubber articles such as old or off-specification tires, wiper blades, or any other rubber materials available. The polymeric binder may be an aqueous rubber latex containing natural or synthetic rubber particles, and which is compatible or miscible with the rubber particles, including, for example, neoprene, styrene-butadiene rubbers, acrylonitrile-butadiene rubbers, high molecular weight olefin polymers with or without other monomers and polymers such as butyl rubber and cis- and trans-polybutadienes. The polymeric binder may also be a polymerizable binder, such as a urethane prepolymer. A suitable composite is described in U.S. Pat. No. 5,723,192, to Jonasz, which is incorporated herein by reference in its entirety. The composite of the patent contains 60-90% (w/w) of rubber particles of a varied sized distribution in the range of 5-30 mesh, 3-20% of a polymerizable material being non-reactive with the rubber particles and polymerizing to form a matrix surrounding the rubber particles, and 0-20% of reinforcing fibers that are non-reactive with the polymerizable material. Particularly suitable polymerizable materials are polyurethane prepolymers which may be polymerize to a polyurethane matrix, and specifically, methylene-4,4′-di(phenyl-isocyanate) and polymers or oligomers thereof having an NCO functionality of from 2.2 to 3, and 4,4,4″-triphenylmethane triisocyanate.

[0017] Cover cap 12 may be produced by a molding process. Such processes are known in the art, for example for tire molding, and will not be detailed here. In particular, a compression molding process may be used, such as that described in U.S. Pat. No. 5,723,192, referenced above.

[0018] In various embodiments, the cover cap of the present invention conforms substantially to the shape of the opening into the underground structure. For example, the cover cap may be circular in cross-section as for attachment to manhole cover 14 of FIGS. 1 and 2, or it may be rectangular, as illustrated in FIG. 3. Cover cap 30 of FIG. 3 is suitable for attachment to a cover for a catch basin, field inlet or drop inlet. Cover cap 30 is pierced with drainage holes 32; these are generally necessary when the cover cap of the present invention is attached to a cover for an underground drainage structure. The particular configuration of drainage holes is not critical, but fluids should be able to pass through the cover cap and access cover readily.

[0019]FIGS. 4a-c illustrate several means for fastening cover cap 12 to manhole cover 14. A layer of adhesive 42 is shown between cover cap 12 and manhole cover 14 in FIG. 4a. Adhesives for bonding rubber to metal are known; any adhesive composition may be used, provided that adhesive strength of the bond is sufficient to prevent delamination under temperature conditions of actual use. For example, an adhesive material that is useful at temperatures ranging from −20° F. to about 100° F. is A-1226-B, available from BF Goodrich, which conforms to standard MMM-A-1617. In FIG. 4b, cover cap 12 is joined to manhole cover 14 by means of a bolt 44. If desired, bolt 44 may be placed within a sleeve (not shown), in order to minimize wear on the rubber material surrounding bolt 44. Bolt 44 passes through cover cap 12 and manhole cover 14, and is fastened by nut 46. Many manhole covers contain holes through which a bolt may be passed; if there is no preexisting hole, a hole sized for the bolt may be drilled through the cover cap and manhole cover at appropriate position(s). FIG. 4c shows a clamp or clip 48 for fastening cover cap 12 to manhole cover 14. Clamp 48 fits tightly over cover cap 12 and under manhole cover 14. Clamp 48 may be composed of hardened steel and is typically about one inch in diameter, and less than ⅛″ in thickness. It will be apparent that other fastening means may be used, as well as other adhesive compositions, bolts and clamps, provided that the cover cap is securely attached under conditions of use.

[0020] In a basic embodiment, the present invention also relates to a method for raising the level of an access cover of an underground structure by a predetermined amount. This method may be used for any manhole cover that is not level with grade, including, for example, low lying field inlet covers, sunken catch basin covers and also, manhole covers set in a roadway which has been or will be repaved. The method includes fitting to the access cover a cap comprising upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, having a thickness generally corresponding to the predetermined amount, and comprising a rubber material. Fitting the cap to the access cover typically involves selecting a cap of the proper size and shape, corresponding to covers which are generally manufactured in standard sizes and shapes. If necessary, or desired, two or more cover caps may be attached to the manhole cover, especially where the predetermined thickness is greater than the thickness of the cover cap. The thickness of the two or more cover caps is typically limited to less than six inches, in order to minimize shifting or the cover cap, and/or delamination. The cap typically overlays the juncture between the access cover and the frame and shields it from water inflow, although, in some cases, it may be desirable for the cap to be the same size as the access cover, or even smaller than it. The cap is then attached to the access cover, using any of the above-described means for fastening the cap to the access cover may be used.

[0021] The invention also relates to a method for repaving a roadway having at least one access cover for an opening into an underground utility structure set therein with a layer of pavement having a predetermined thickness. The method includes fitting to the access cover a cap comprising upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, having a thickness generally corresponding to the predetermined thickness and comprising a rubber material; attaching the cap to the access cover; applying the layer of pavement to the roadway such that an upper surface of the cap is substantially flush with the upper surface of the layer of pavement; and contacting the outer edge of the cap with the layer of pavement.

[0022] While the invention has been described in detail herein in accordance with certain preferred embodiments thereof, many modifications and changes therein may be affected by those skilled in the art. Accordingly, it is intended by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention. 

1. A cap for an access cover for an opening into an underground utility structure, the cap comprising upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, and comprising a rubber material.
 2. A cap according to claim 1, wherein the access cover is seatable in a frame in the opening into the underground utility structure and the cap is adapted for disposition over at least a part of the frame, whereby a juncture between the access cover and the frame is shielded.
 3. A cap according to claim 1, wherein the rubber material comprises rubber particles.
 4. A cap according to claim 3, wherein the rubber material additionally comprises a polyurethane binder.
 5. A cap according to claim 3, wherein the rubber particles are derived from used vehicle tires.
 6. A cap according to claim 1, having a circular cross-section.
 7. A cap according to claim 1, having a thickness of at least 0.5 inches.
 8. A cap according to claim 1, additionally comprising drainage holes.
 9. A cap according to claim 1, adapted for attachment to an upper surface of the access cover.
 10. A cap according to claim 1, additionally comprising means for attaching the cap to the access cover.
 11. A cap according to claim 10, wherein the cap is attached to the access cover by an adhesive.
 12. A cap according to claim 12, wherein the cap is attached to the access cover by at least one bolt.
 13. A cap according to claim 12, wherein the cap is attached to the access cover by at least one clamp.
 14. A method for raising the level of an access cover of an underground structure by a predetermined amount, said method comprising: fitting to the access cover a cap comprising upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, having a thickness generally corresponding to the predetermined amount, and comprising a rubber material; and attaching the cap to the access cover; whereby the level of the access cover is raised.
 15. A method according to claim 14, wherein the cap is attached to the access cover using an adhesive.
 16. A method according to claim 14, wherein the cap is attached to the cover using at least one mechanical fastener.
 17. A method according to claim 16, wherein the mechanical fastener is a bolt.
 18. A method according to claim 16, wherein the mechanical fastener is a clamp.
 19. A method for repaving a roadway having at least one access cover for an opening into an underground utility structure set therein with a layer of pavement having a predetermined thickness, said method comprising: fitting to the access cover a cap comprising upper and lower opposed surfaces and an outer edge having dimensions substantially conforming to dimensions of the opening, adapted for attachment to the access cover, having a thickness generally corresponding to the predetermined thickness and comprising a rubber material; attaching the cap to the access cover to form a cover cap combination; and applying the layer of pavement to the roadway such that an upper surface of the cover cap combination is substantially flush with the upper surface of the layer of pavement.
 20. A method according to claim 19, additionally comprising contacting the outer edge of the cover-cap combination with the layer of pavement.
 21. A method according to claim 19, wherein the rubber material comprises rubber particles derived from used vehicle tires.
 22. A method according to claim 19, wherein the rubber material additionally comprises a polyurethane binder. 